Approximately 90% of aging and medical research with mice uses single inbred genotypes, which can lead to weak offspring and strain-specific traits.

“are we talking less than 10 oh yeah much less than 10 and the reason is that when people want to work in aging they call the nia the national aging institute and they say can i please have some old mice and the nia does not have genetically heterogeneous mice they had them for i begged and pleaded and kicked and screamed as did some colleagues and they set up a colony of genetically heterogeneous mice and after three or four years they were not receiving many requests everybody was saying i want black six mice my scientific parents use black six mice and everybody always uses black six mice so the nia for lack of demand folded up the colony”